The study examined the inner workings of the brain, monitoring the activity level of the amygdala in response to a series of faces. The amygdala triggers human response to social and emotional behaviors.
Participants were first shown photographs and then computer-generated integrated images of faces that accentuated "untrustworthy features," such as higher inner eyebrows and pronounced cheekbones. When researchers increased the speed of how quickly participants saw alternating images, the report noted changes in participants' amygdala within milliseconds of being shown a new image.
People possess a keen ability to sense when something isn't right, says Joe Navarro, retired FBI special agent and author of Dangerous Personalities. "Whatever you want to call it, it is often an intangible feeling that we have that something isn't right, that something is odd or weird—it can be about a location in a darkened neighborhood or someone we meet for the first time."
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Navarro's work investigates how to handle judgmental tendencies by assessing what people are transmitting emotionally between each other. "We all decide who we let in to our house—otherwise everyone gets in," he says.
Your personal life is yours to post as private property, but if you're more into being a gatekeeper than building a moat, here are his tips to make sure the door doesn't swing open for the wrong people. Hospitality is great, but don't let good manners overrule your instincts.
Listen to Quiet Signs
If your hair stands up, your hands start to sweat, your throat becomes dry, or your heart starts pumping when someone walks in the room, it's time to tune into your body's way of quietly telling you something's wrong, says Navarro. "The first thing is to recognize your feelings," he says. If you start to feel bad vibes, see if the unease is lifted when a person leaves the room.
Set Your Perimeters
Predators will want to dominate your space, time, attention, and ultimately, free will. Nosy neighbors or solicitors who can't take no for an answer are easy to spot when they're standing in your doorway, but there's also reason to note individuals invading your space from afar.
Watch the Clock
Sometimes a stare or a gaze makes us uneasy because of the person's intensity, explains Navarro. Take note on how long someone's eyes are locked on you. Too long can mean you're a target.
Don't Brush Off Danger
If someone is making you uncomfortable, even at a distance, don't ignore it, says Navarro. Keep your distance; establish your time and area as your own. "There is a place for avoidance and distance, and it is your right to exercise at any time," he says.
Evaluating someone's trustworthiness goes beyond which family you'd leave with your kids or what friend you'd entrust with your fantasy lineup. With an acquaintance, sometimes all you need to know is in the initial "Hello."
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Find more tips for protecting yourself in Joe Navarro's book Dangerous Personalities.